Mo. Rev. Stat. § 67.318

The governing body of any county or municipality may by order or ordinance require that all residences and commercial businesses have the numbers of their street addresses conspicuously posted so that providers of fire protection services or other emergency services may better find the proper location when responding to an emergency call. Where such an ordinance or order is established, the fire department, fire protection district or volunteer fire protection association which provides fire protection services for the municipality or county, or portion thereof, shall enforce the provisions of such ordinance or order. The ordinance or order shall prescribe a grace period for persons who violate the ordinance or order, which shall allow such violator at least fifteen days to comply with the ordinance before any fine may be imposed.